Red Wizard have to access the circle magic ability, a powerful mechanic that allows you to drain power from other characters with the Tattoo Focus feat and use it to increase your own caster level or apply metamagic feats to spells without altering the spell level. While one can only apply Heighten, Maximize, or Empower to the given spell, knowledge of these feats is not required to perform the operation.
Meanwhile, your caster level can be raised to a maximum of 40th. This increase alone can practically heighten, widen, and enlarge all of your spells, to say nothing of the difficulty another wizard will have in attempting to dispel them. There is no limit to the number of times per day that a caster can use circle magic, but each usage requires 1 uninterrupted hour.
The most optimal thing to do with Circle Magic is probably to just raise your caster level as high as it will go, since this affects all of your spells, making your Black Tentacles, Telekinesis, and Mental Pinnacle far more dangerous than those of your weakling brethren. If you have the opportunity to extract more circle levels, say because you are using your Simulacra as fuel, consider applying as much metamagic as you can to your most powerful attack spell. This spell will remain in your mind until you cast it, so by being conservative you can over the course of a few days build up a suite of several immensely powerful spells.
The difficulty in using Circle Magic is simply one of finding appropriate and willing participants to donate their spells for your greater glory. There are several ways to accomplish this.
Taken from http://community.wizards.com/go/thread/view/75882/19869014/Red_Wizard_Handbook . 22.214.171.124 10:25, May 28, 2010 (UTC)